Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology, Guilin University of Technology, Guilin 541004, China; College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China; Department of Geology & Geophysics, Texas A&M University, College Station 77843, USA.
Guangxi Key Laboratory of Environmental Pollution Control Theory and Technology, Guilin University of Technology, Guilin 541004, China; College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China.
Int J Biol Macromol. 2021 Mar 1;172:197-209. doi: 10.1016/j.ijbiomac.2021.01.060. Epub 2021 Jan 13.
This study is the first to evaluate the effects of Iron oxides (FeO) species and their decoration on graphene oxide/chitosan (GO/CS) composites for Cr(VI) removal and the possibility of Fe secondary pollution. Results show that Fe(III) is a better decoration material than Fe(II) and decoration through immersion-evaporation shows a higher adsorption capacity of Cr(VI) (Q) than co-precipitation. FeO-GO/CS as the only eco-friendly composite for enhanced Cr(VI) removal is further used for batch adsorption experiments, characterization, kinetics, isotherms, and thermodynamic studies. It is found that Cr(VI) removal mainly includes electrostatic attraction between Cr(VI) oxyanions and surface -NH and -OH, and the adsorbed Cr(VI) partially reduces to Cr(III). Q increases with the increasing initial Cr(VI) concentration, contact time, and temperature, while decreases with the increasing pH and mass and volume ratio (m/v). The coexisting ions (Cl, NO, SO, PO, As, Fe, and Pb) can cause an obvious decrease of Q. The removal efficiency (R) and Q are 94.3% and 83.8 mg/g, respectively under the optimal conditions. After five times of regeneration, R is still as high as 84% and Q drops about 2.6%. Cr(VI) adsorption is spontaneous and endothermic, which is best fitted with the Sips model, and the fitted maximum Q is 131.33 mg/g.
这项研究首次评估了氧化铁（FeO）物种及其在氧化石墨烯/壳聚糖（GO/CS）复合材料上的修饰对六价铬（Cr(VI)）去除的影响，以及可能产生的铁二次污染。结果表明，Fe(III)是一种比 Fe(II)更好的修饰材料，且通过浸渍-蒸发法修饰的复合材料对 Cr(VI)的吸附容量（Q）高于共沉淀法。FeO-GO/CS 作为唯一的增强 Cr(VI)去除的环保复合材料，进一步用于批吸附实验、表征、动力学、等温线和热力学研究。结果发现，Cr(VI)去除主要包括 Cr(VI)含氧阴离子与表面 -NH 和 -OH 之间的静电吸引，以及部分吸附的 Cr(VI)被还原为 Cr(III)。Q 随着初始 Cr(VI)浓度、接触时间和温度的增加而增加，随着 pH 值以及质量和体积比（m/v）的增加而降低。共存离子（Cl、NO、SO、PO、As、Fe 和 Pb）会明显降低 Q。在最佳条件下，去除效率（R）和 Q 分别为 94.3%和 83.8 mg/g。经过五次再生后，R 仍高达 84%，Q 下降约 2.6%。Cr(VI)吸附是自发和吸热的，最符合 Sips 模型，拟合的最大 Q 为 131.33 mg/g。
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